In an internal combustion engine, connecting rods are often provided to connect a reciprocating piston to a rotating crankshaft. The connecting rod assembly is often sturdy and designed to bear the load of combustion while undergoing reciprocating and rotary motions. The assembly layout may comprise three basic parts: a first end connected to the piston, a second end connected to the crankshaft, and a beam that connects the first end to the second end. Typically, the first end is smaller than the second end. The first end may contain a cylindrical hole, which receives a steel pin (“wrist” pin). The wrist pin may be mounted, for example, on opposed sides of a piston skirt. The wrist pin may allow the rod to transfer the reciprocating motion of the piston to the rotary motion of the crankshaft.
The second end of the connecting rod assembly may have a larger cylindrical opening that conforms to the shape of the journal of a crankshaft pin (“crank pin”). The larger opening may be formed by two separate pieces for enclosing the crank pin. The larger of the two pieces may consist of a small end, an intermediate beam and a portion of the large cylindrical opening for the crank pin. The smaller of the two pieces may comprise an end piece or bearing cap, which provides the remainder of the large cylindrical opening. The larger piece may be designed to fit around one side of the crank pin. The bearing cap may be designed to fit around the other side to enclose the crank pin. Retaining means such as bolts may be utilized to connect the bearing cap to the larger portion of the connecting rod assembly to complete the connection of the piston to the crankshaft. Bearing inserts may be used when mounting the assembly on the crank pin to allow the rod to move freely.
Hence, connecting rods may typically have two-piece crankpin bearings for connecting the lower end of the rod to a crankpin of a crankshaft. The two-piece assembly may comprise an arcuate-shaped bearing portion integrally formed on the lower end of the rod, and a cap member, which is assembled to the bearing portion by means of a pair of cap screws.
Lubrication may be provided between the relatively moving crankpin and crankpin bearing parts, through bores extending radially through the crankpin bearing. The bores may have an inlet located at the exterior surface of the crankpin bearing and an outlet communicating with the crankpin bearing hole. The bores provide oil to the interior of the crankpin bearing during operation, and, in particular, during startup of an engine, can quickly supply oil to the interior of the bearing.
In some previous designs, a connecting rod may include designs for conveying lubrication into a crankpin bearing. However, such connecting rod designs may not provide sufficient lubrication to bearing surfaces since, for example, the design may not allow lubricant to flow sufficiently in order to reduce friction as the connecting rod rotates.
Accordingly, it is desirable to provide an apparatus that may provide improved and/or constant lubrication to bearing surfaces. It is also desirable to provide an apparatus that extends the life of bearing surfaces by supplying and retaining lubricant upon the surfaces thereon and minimizing frictional contact between bearing surfaces.